Mitochondrial DNA (mtDNA) mutations are associated with various disease. Recent studies have shown that there is a close association between the nt 3243 of t RNA^<Leu(UUR)> gene (A3243G mutation) and maternally inherited diabetes mellitus (DM). Multiorgan involvement has been suggested. As a test of exocrine pancreatic function, we performed a bentiromide test using benzoyl-tyrosyl-p-aminobenzoic acid (PABA). % recovery of PABA decreased at a range 19-68% (cf normal 81.9 8.5% ; DM 77.0 12.6%). The percentage of mutant mtDNA ranged from 6-63%. This result indicated that exocrine pancreatic dysfunction may be associated with the A3243G mutation. We have calculated the prevalence of spontaneous abortion in 379 women who delivered children in our hospital. The prevalence of spontaneous abortion was 14.4% (spontaneous abortion/total pregnancy=96/717). In our study, the prevalence of spontaneous abortion was higher in the population with the mutation than that of general population (25.0 vs
… More13.4%). In the basic study, we used C_2C_<12> myoblast treated with ethidium bromide 250 ng/ml for 10 days in medium. The cell line C2C12 was treated with EB for 10 days, and total RNA extract from cells from the cells. After 10 days incubation with EB, no mtRNA was detectable in C_2C_<12> cells, but the contents of beta-actin were not affected. After 60% confluent, we changed medium to 2% horse serum, 50 mug/ml uridine and 0.1 mg/ml pyruvate. Differentiation to myotubes in C_2C_<12> cells with EB was remarkably impaired. We also study the effect of EB in differentiated C_2C_<12> myotubes on insulin stimulated glucose transport. C_2C_<12> myotubes were treated with EB 3 days, and 2-deoxyglucose transport was measured. Insulin-stimulated glucose transport activity was decreased in C_2C_<12> myotubes treated with EB.In conclusion, we observed variable clinical symptoms in the patients and lacking of mtDNA induced a impaired muscle differentiation and its function in culture cells.necropcyの症例は下痢等の膵外分泌障害の臨床症状を認めた症例であったが、その電子顕微鏡所見は粗面小胞体と分泌顆粒の喪失と空胞変性しミトコンドリアの所見を呈していた。さらにtransferRNALue(UUR)変異の症例において、うつ病の原因となっていることを示唆する症例を報告した。さらに生殖にも重大な影響を及ぼし、胎児の発育障害、自然流産の頻度が高いことを明らかにしてきた。また、胃酸分泌機能、腸管運動機能など消化器機能の研究をすすめ、mutant mtDNAのを有する症例に麻痺性腸閉塞を起こしうること、実際穿孔症例を報告した。細胞レベルの検討ではインスリン作用の主要な標的臓器である筋肉と脂肪組織の培養細胞系であるC2C12細胞と3T3-L1細胞を用いて実験を行った。各々の培養細胞を分化させる前にエチジウムブロマイド(EB)処理を7日間行い、分化誘導を行うと、いずれの細胞においてもmtRNAの発現は検出されず、筋細胞への分化、脂肪滴の貯留は抑制された。また、分化したC2C12細胞にEBを添加し3日間培養するとインスリン刺激による糖輸送活性は約40%抑制された。これらの結果はmtDNA異常が直接にインスリン作用を障害し、また筋肉の異常を示唆すると考えられる。さらにmtDNA遺伝子を導入し、これらの障害を改善しうるか検討をしている。 Less